Posted
by
Soulskill
on Sunday April 18, 2010 @11:21AM
from the did-we-forget-to-sacrifice-somebody dept.

chrb writes "As we discussed on Friday, the eruption of Eyjafjallajökull in Iceland has led to flights being canceled across the EU. With travel chaos ensuing and the airlines losing an estimated $200 million per day, EU authorities are coming under increasing pressure to re-open the airways. Test flights conducted on Saturday were apparently successful, with no problems encountered during flight. Following the test flights, Peter Hartman, CEO of KLM, said, 'We hope to receive permission as soon as possible after that to start up our operation and to transport our passengers to their destinations.' Evidence possibly opposing this move comes from the Finnish Defense Forces, which released photos and a statement after F-18 Hornets flew through the ash cloud, saying, 'Based on the pictures, it was discovered that even short flights in ash dust may cause significant damage to an airplane's engine.' Is it safe to resume flights so soon, or should planes remain grounded until the ash cloud has dissipated?"

So we can choose between the findings of a massive corporation intent on re-establishing its cashflow as soon as possible or a military entity performing a post-mortem on its equipment which sustained damage just prior to flight restrictions.

Ash is abrasive. Any idiot who has washed their hands with LAVA soap can attest to that.Q:So then, what happens when you put abrasives into parts manufactured to close tolerances?A: Tolerances are widened.Q: What happens when tolerances are widened on machinery that spins at high RPM?A: Centers are lost and jitter occurs speeding disappearing tolerances and adding heavy vibration.Q: What will that heavy vibration do Cap'n fly?A: Titaniums can shatter, Waspalloy and Hastalloy parts will tear away from Titaniums and Aluminums, H60 coated bearings will fly as though fired from a gun.Q: What are you really saying, fly?A: Assume the crash position, put your chin on your taint and kiss your @ss goodbye!

Ash is abrasive. Any idiot who has washed their hands with LAVA soap can attest to that.

LAVA soap isn't made of ash, dumbass, it's made of pumice. Pumice is a product of volcanoes, but not one that goes floating in the air (it does go hurtling through the air, but that's different). It is also thousands of times more coarse than ash - ash is finer than the finest sands you can find. The individual grains are extremely hard and jagged, and thus very abrasive, but they will also move largely with the air - i.e. as the jet engine creates a flow through it, most of the ash is going to pass righ

Volcanic Ash is essentially magma mist. when you get down to the quick and dirty of it, it's almost like having pulverized pumice. It's very glassy in texture, and very VERY abrasive, unless it's been weathered down over a few thousand years.

This fresh stuff can make your eyes and nose itch, it can and will stick to all sorts of parts, it gets EVERYWHERE. Having walked through an area where an ash cloud immediately settled, I can attest to the fact it can and will stick to you, you have to brush it off well to even begin to get it out of all sorts of small places.

Imagine what it will do to a jet engine, it will collect, and slowly clog the engines.

To me, it sounds like a bunch of airlines willing to risk the lives of their crews and their passengers to resume making money, even though they face multi-billion dollar class action lawsuits when something happens at a later date due to damage to the engine internals.

oh not to mention engine repair.

These are the same airline companies that still fly poorly maintained planes that were built in the late 70's and early 80's.

I'd trust the finnish on this. This "Ash" is not the same as the ash you get from a fire. It's much more coarse and grainier. go rub some fresh volcanic ash against your skin and then tell me you wont be itchy and a red mark will be left behind.

Well, as fresh as it will be once cooled down from being thousands of degrees in temperature.. in the middle of the air.

1. Windshields will get sandblasted. Maybe not during one flight, but give it a week or two and they'll bereplacing their windshields. $100k is the order of magnitude I believe.

2. Every part of the engine that runs at high temperature will get ash caked on it. Does wonders tohigh pressure turbine efficiency. I don't know if APUs on modern airlines power hydraulics, but they betterdid, and you better hoped that the APU will survive the ash treatment as well.

3. Seals that are airtight usually are not dust tight -- I know, it's counter-intuitive, but that's how it is,especially with seals over rotating shafts. The oil in those engines will make sure that the ash is redistributedto the bearing surfaces running at highest temperatures -- where it can do most damage.

When you get crap caked on inside of the engine, you don't "replace things earlier". You're talking aboutreplacing the engine, and doing a full overhaul on the one you took out. Figure $1M o.m. for two high bypassturbofans maybe?

Actually the problem, as I understand it, is that the silica particles in the ash cloud (similar to very fine grains of sand, or glass) are melted by the heat of the engine, then then collide with the leading edge of the turbine blades and condense. This is bad for a number of reasons, firstly it expands that surface and significantly reduces the efficiency of the engine. More importantly however, it has a different coefficient of thermal expansion to the titanium blade, and very quickly it will start to crack and break away. In this process it takes small chunks of the blade with it. The process causes a lot of pitting in the leading edge of the blade.

The thermal spraying department at my work do a lot of research into repairing blades that have suffered from this problem. Most often it has been caused by planes flying through sand storms in a desert, but the effect is just the same. One of the methods of repairing the blade is to remove enough of the titanium so that you can plasma spray a ceramic in its place to make the blade the right size again.

The problem is that nobody's measured the actual concentration of the ash cloud yet. The satellite images show SO2, not the solid particles. No airline would willingly or even just carelessly fly their planes through ash: The repair costs for a whole fleet would be astronomical. The question they're trying to get answered is this: Is the simulation, which is the current source of information, accurate or is there airspace which is usable without damage to the machines and risk to the crews and passengers? F

I don't know if you know this, but big corporations don't get to be big corporations by spending more money in repairs than they receive in receipts. In other words, if the big corporations are clamoring to get back in the skies in the middle of a volcano after verifying the safety of the passengers, you know damage to equipment is going to be less than the receipts they'll get from flights.

In other words, as long as the safety of the passengers is maintained, who the hell cares if they fly? If you're concerned about flying through an ash cloud and don't want to "risk it" (even though there is likely little or no actual risk to you), then don't buy the damn ticket and don't get on the damn plane.

If you're concerned about flying through an ash cloud and don't want to "risk it" (even though there is likely little or no actual risk to you), then don't buy the damn ticket and don't get on the damn plane.

Where have you been for the last 50 years of ever increasing liability lawsuits? Even if you could get all of the people on board to make a statement about acceptable risk then in the off chance of a crash the survivors would sue that the risks weren't actually made clear to them and the families of the dead would sue that they weren't willing to take the risk of losing that person. Personal responsibility = dream on. In light of this trend, I think if the airlines are willing to start the flights again then it's probably OK. KLM, BA, etc, These aren't some disount airlines in third world countries. They manage risk quite well.

Even if you could get all of the people on board to make a statement about acceptable risk then in the off chance of a crash the survivors would sue

Screw the survivers. The plane crashes into an apartment block. The obvious conclusion from the NTSB is that the crash caused by the volcanic ash breaking the engine, plugging the pitot tubes [wikipedia.org], taking out all electrical systems and making the cockpit windows opaque.

I'm sure the jury in any kind of lawsuit resulting from this crash will agree that the fact that th

And here's the gotcha, they never disclosed how close to the volcano the finn planes were.

Do you think it is safe to say that they were about as far away as Finland is to the volcano? Say 2500km. Or do you think they said, "hey there's a volcano erupting 2500km away that we'd have to cross three sovereign nations airspace's with in our military jets (Finland doesn't belong to NATO or any common EU defense alliance), let's go fly our planes over there." Personally I would tend to believe that they flew over their own country and decided to do a 'post-mortem' on the engines when they found out how bad the ash cloud was.

1. You're saying that they were lying when they said that they had practice mission in Nothern Finland. And lied that even short missions can cause problems when they released photos about the engines.

2. You think that they _could_ lie about it and not get caught. Do you have any idea how closely airspace is being scrutinized?

1. You're saying that they were lying when they said that they had practice mission in Nothern Finland. And lied that even short missions can cause problems when they released photos about the engines.

No, I'm saying I saw only one source claiming they were on Northern Finland. Maybe they were further north, in the arctic.

And I'm sure they're being 100% honest about the engine photos.

Well. The original source is the Finnish Airforce. And plese do check the map. Further North doesn't really cut it. Yes, I saw the flightplan map, where the Iceland was 1380 miles away. To the West of Finland, through both Sweden and Norway.

A part of story behind the photos was that they said that even a short flight was problematic. I don't think a flight to Iceland and back would count as one.

2. You think that they _could_ lie about it and not get caught. Do you have any idea how closely airspace is being scrutinized?

Depends on altitude, artic monitoring and radar signature of the F-18. I'm not sure they ask civilian ATC for clearance...

You generally don't fly your military jets through other countries. For example, it gets to the news if a Russian

Come on, this is Slashdot. Most people who haven't ever left their native area are oblivious to where other places are. You could ask most Americans where the border between Quebec and British Columbia is, and they'd point to some arbitrary place. I'd be willing to guess at least half may point to somewhere in Canada. Some may see "British" and point to somewhere in or near the UK.

The issues here also have to do with melting, heat of crystallization, size of openings where the fuel injectors are concerned, durability of the turbofans etc etc. I can easily imagine the characteristics of one engine making it suffer much less harm than another of even slightly different design. What I can't imagine is figuring out which ones would fall into which category based on the information we have.

Peter Hartman, CEO of KLM ended the interview with the thoughtful remark that, "As a further comfort to our esteemed customers, all seats are now equipped with their own personal parachute. Preliminary research has suggested that those lucky passengers seated direly by the emergency exit increase their odds of successful 'emergency sky-dive' by a factor of 1000 over those in normal economy class, provided that they time their exit and decent to the appropriate altitude, or are just able to hold their breath

I could just see something like that happening. A plane going down with no power and no controls, passengers going to the nearest exits. People getting stomped on trying to make their way to the exits. Some people jumping out the front doors, just to get hit by the wing or engines. Oh and of course those people who panic at the last second and can't step off the ledge. How many people can they get from a plane from under 10k feet before it hits the ground? I think most peoples chances

I think that 'Better safe than sorry' is a good way to handle this... however straight after closing the airspace there should have been real tests going on how much ash there actually is. The warnings given by the Volcanic observation center are just based on simulations and there is no middle way between 'ash' and 'no ash' currently.I totally understand that the airlines are starting to complain - even more when they have to _prove_ themselves that there is no problem with low concentrations.There hasn't been any weatherballoons or similar testing by the governments right after closing the airspace.

How do you do those 'real tests' without running expensive aircraft through the target airspace? Although clearly we have had some experience with volcanic ash, from what I've read there is a real dearth of information. I imagine (although it really hasn't shown up in the news) that various smart and inventive persons are trying to run through ideas to sort this out.

Remember, the real issue is what is going on between 10000 and 30000 feet. Hard to walk there and sample some air. Modified radiosonde ba

You send disposable aircraft with a prop (not a turbine engine) that can take samples at (relatively) low speeds.

That may be valid for low values of 'disposable' but I don't think the DOD wants to send their fleet out there. Those puppies are fairly expensive. They also are single engine so if anything happens, the platform goes splat (hopefully not into something important).

Right now it seems we're relying on satellite information (note to idiots who don't think space flight is important -- think ag

That animation isn't based on a measurement though, it's based on a computer simulation with debatable accuracy (whose initial conditions were based on some measurements, again with debatable accuracy).

I totally understand that the airlines are starting to complain - even more when they have to _prove_ themselves that there is no problem with low concentrations.

I understand too and don't care. I don't care if they're losing $1,000,000,000,000,000,000,000... a day or more, it just doesn't matter. Volcanic ash is highly abrasive, has high concentrations of glass rich particles and will cause significant wear on machinery parts, like jet engines You cannot make one test flight through the stuff and safe all is safe for normal airline operations. Fly through it a hundred times and see what happens. Greed is never a reason to find a way around safety.

It will only kill an engine when sufficient amounts have built up to cause enough airflow disruption. Such an amount is easily observable after each flight. The engines can have maintenance done at the appropriate time. Presently large amounts of European airspace have very small concentrations of ash between certain latitudes. Jetliners can fly below this layer as well as above it at 38,000 feet. They can take off and if deemed necessary, fly several hundred miles under the layer to a thinner area, ascend

This links leads to a page with a video of an ambulance helicopter that was coated in a fine layer of ash in Norway today. It flew during a small windows of opportunity where the air cleared to pick up a patient in Sweden. The link is in Norwegian, but the video is, obviously, visual.

Note that the ash is also acidic. When you get to clearing it off, bear that in mind.

Attempting to brush it off will be fairly damaging. Washing it off with water could be a problem too. Best bet is probably very large quantities of water to dilute anything faster than it can cause damage.

The question here is - how long will the eruption and the ash cloud last? Judging from historical records, it's not uncommon for eruptions to last decades. If - then what? New routes? Limit cross-atlantic flights endpoints to southern Spain or something?

The question here is - how long will the eruption and the ash cloud last? Judging from historical records, it's not uncommon for eruptions to last decades. If - then what? New routes? Limit cross-atlantic flights endpoints to southern Spain or something?

According to this article [sciencedaily.com], it may last for another month, and possibly a year or longer. It will be interesting, if somewhat uneasy, to see how people will react to this (boats to the US? fly above/below the ash clouds?). Clearly this cannot go on for long, given the damage that it is doing in terms of lost revenue for businesses, mail not being delivered (so i hear) and thousands of stranded customers.

I wonder if something that makes this volcano different than all other volcanoes is that it's erupting at a time when almost all translatlantic flying is done on two-engine planes. To get long-range over-water certification (ETOPS), the manufacturers and maintenance organizations go to great lengths to ensure that there is no common threat to the two engines. The engines are serviced separately by independent crews, fueled separately, and so on. Flying into an ash cloud, though, even if the threat is small, it is certainly a common threat to both engines at the same time.

I was looking for flights to Europe recently, and couldn't find a single 747 or A340 -- it was all 767, 777, or A330. I know 747s fly those routes, but they are a small minority now.

Four engines vs. two engines doesn't really matter. Some of the most dramatic incidents of airplanes ingesting volcanic ash are 747s. Invariably, every single engine shuts down after several minutes of sucking up ash and melting it into glass. All four engines have to be restarted to recover, once the airplane descends out of the cloud and the glass has time to cool off.

I think that a 747 can operate on 1 engine alone as well, in that case go through the ash cloud with only one engine running and as soon as you cross the cloud start the other 3, or do it with 2 engines running initially, if 1 fails in the ash cloud then start a 3rd engine, hopefully by the time you are out of the cloud atleast 1 engine will be working.

Then when the conditions are right, all 4 engines can be started back up..

I wonder if something that makes this volcano different than all other volcanoes is that it's erupting at a time when almost all translatlantic flying is done on two-engine planes.

Probably not. Ash has caused all engines to go out on a 747. As you say, the threat is common to all engines, whether 2,3, or 4.

The airlines have it right. All the talk has been about flights being canceled for a few days or weeks, but as far as I can tell there's no real reason the eruption couldn't continue for months, and plenty of precedent for eruptions which have. And talk about the wind shifting seems pretty much wishful thinking as well; the upper air westerlies aren't going to stop blowing eastward, nor are they likely to lose all their southward components. So a very conservative approach (no flying until the ash has dissipated) could result in most of northern Europe being a no-fly zone for months. It's probably worth the risk to find out more precisely where the conditions really are too dangerous.

One thing no one seems to have brought up in response to this article so far regarding the length of the eruption is that it's not simply the fact the volcano is erupting, and it's not simply the fact that it's erupting in a location where ash is carried by the jet stream.

The issue is the strength of the eruptions. The initial eruptions were of course quite powerful, and these were forcing up sizeable chunks of silica and such into the air which really were quite dangerous, however as the eruption continues

So based on a few low altitude flights they want to reestablish about 20k flights / day? It's excellent that 5-10 testflights could manage in low altitude, however if only 0.1% flights drops out of the skies, that is still 20 flights downed per day. You don't establish safety based on limited tests.

Sure it's possible that the computer models establishing the extent of the dust cloud are conservative towards safety, however isn't that what you would expect no matter how much it costs the airlines? The Finnish incident clearly shows it's not safe, at this point I'm not even sure I'd trust the airlines to disclose whether they suffered damage in their test flights.

They're the ones who'd have to pay if an accident happened, they're the ones who own the aircraft, they're the ones who best understand the risks involved. Even in a much more intense cloud of ash, closer to the volcano which was at a higher altitude, which caused 4 engines to shut down (BA9, the textbook example) 3 of 4 engines started up once they got out of the ash cloud.

Meanwhile all planes grounded over a risk that experts don't think is credible means vacations ruined, investments lost, business tr

The ash allegedly contains shards of glass, and I can see how this would cause serious problems for turbines... but I think it's obvious that just like any other phenomena of weather, the ash will be non-uniform. It makes perfect sense that one test would have completely different results from another. Thus, broadly-based testing would be necessary to derive any useful result...

Indeed. In fact the height the ash plume reached has changed from Wednesday to Saturday from 8 miles down to 3:

In Iceland, the volcano continued to erupt, but volcanologists said was it less explosive than at the beginning of the eruption on Wednesday, which blasted glassy abrasive ash, destructive to jet engines, eight miles into the sky. The plume was now rising to a height of just three miles, and the volcanologists said this would deposit ash only in Iceland and in the surrounding waters. It was not hi

I don't know enough about the extent of the ash cloud to make a decision about this. In fact, I suspect no one knows much about it and that's the crux of the dilemma. I do know that when Mt. St. Helens erupted the area where I live was seriously impacted by the ash and many vehicles were severely damaged. Of course, this area was only 150 miles east of the volcano and the ash cloud was dense enough to block out the sun. The ash cloud over Europe is likely to be much less dense. I have been an airplane and glider pilot since 1970 and I, personally, would not want to risk flying until I understood more about the risk.

As an ATPL pilot, any idiot who flies into the dense components of the ash cloud will get absolutely no sympathy from me when they suffer from multiple system failures. Important to note though, the article doesn't mention the density of the ash cloud they flew through. Also, I highly doubt they'll readjust the maintenance cycles of the parts to cater for the increase in wear and tear, so even if the aircraft does not have a problem immediately I'd place bets that parts will fail prematurely in the future.

Tell the airlines and the passengers that they fly at their own risk, and that the government doesn't recommend that they fly due to the hazard.
If people want to fly expensive airplanes through this, and risk their loss without insurance (which I believe would actually prevent this) or government help in paying for the loss, fine. If passengers want to risk their lives this way, fine.

...and also risk the life of innocent bystanders on the ground? You know, if you throw up a few tonnes of metal and plastic, it'll come down eventually and potentially kill people when it lands on their heads.

and it is interesting how the skies are clear of contrails, and also the lack of periodic flights from the local airport, the landing path for which is *directly* overhead at an altitude of a few hundred metres. This includes turboprop aircraft like the Dash jobbies being grounded.

Of course everyone is talking about stranded passengers, nobody is talking about stranded air mail and stranded cargo.

It is interesting to me just how dependent we (and we in Europe are a lot less dependent on flights than USAians) have become on the jet aircraft, and how useless people have become, they just sit in the airports expecting some one else to get them to their destination...

ferries, channel tunnel, trains, automobiles, nope, just won't do... I have driven from London to Athens in less time than many of these people have been sat in airports wringing their hands... I also suspect that it may be CHEAPER to hire a car and drive back home, than to attempt to live in an airport for a week.

interestingly, lots of travel insurance companies are simply shrugging their shoulders when people try to make claims over this, sorry, act of god, not covered by insurance.

BTW, back in the day, we used to hear the sonic boom from Concorde, I have heard some talk that while a 747 cruises at 39,000 feet, Concorde's ceiling of 60,000 feet meant that it could have flown OVER these dust clouds...

ferries, channel tunnel, trains, automobiles, nope, just won't do... I have driven from London to Athens in less time than many of these people have been sat in airports wringing their hands... I also suspect that it may be CHEAPER to hire a car and drive back home, than to attempt to live in an airport for a week.

I know a few people that are stuck across the Atlantic from their homes, that really has to stink. A bunch of them had to go on business trips (separate locations) and are now stuck.

I guess there's always the ship / cruise option but I imagine those tend to be a tad more expensive than a company would want to pay for. Especially when they can go to another work-site and use their network to do some of their tasks.

I've taken the train around, even though co-workers prefer to fly. They claim "well the flight's only an hour..." Yeh, but between security and delays you're only really saving an hour over the train. Heck, splurge on 1st class and it's about the same price and quite a pleasant experience to ride the rails for a few hours.

The helplessness of the average human is a global phenomenon. Of course, airlines don't help much. I once had the first flight in my itinerary canceled, and while I was waiting in line with the other 100 passengers from that flight to take care of it, I also called the airline's customer service line. I offered to rent a car at my own expense and drive it to the hub airport, but they wouldn't accept that since it was more than 300 miles away. And, of the 3 airports they served within 300 miles, there we

As far as I know, much of the dust around Europe is below the cruising altitude of ordinary jets. The problem is however getting from the airports to that height (not to mention short-haul that wouldn't go so high in any case).

ferries, channel tunnel, trains, automobiles, nope, just won't do... I have driven from London to Athens in less time than many of these people have been sat in airports wringing their hands... I also suspect that it may be CHEAPER to hire a car and drive back home, than to attempt to live in an airport for a week.

Sure, if you knew ahead of time it would be a whole week before air travel resumed again. The first reports I heard were that travel was only suspended until friday, so I'm sure a lot of people h

ferries, channel tunnel, trains, automobiles, nope, just won't do... I have driven from London to Athens in less time than many of these people have been sat in airports wringing their hands... I also suspect that it may be CHEAPER to hire a car and drive back home, than to attempt to live in an airport for a week.

I guess you haven't been reading the stores about the Eurostar and the ferry companies having their busiest days ever. Or the thousand euro taxi rides many are resorting through. Have you conside

1. No, "staying at the airport" is not more expensive for the travellers, even in force majure sitations like this, aviation companies are required to pay for the customers hotel and give enough money/coupons for travellers to eat.

2. People are scrambling for alternative transportation - only those going across the pond are in a really big mess, everyone else are being put on trains, busses and even taxis to get to their destinations (aviation companies are required to give alternative transportation and in

The main plume of the ash blows right across the Shetland islands pretty close to Iceland. The maps with artificial color show it to be black here, any yet, I see nothing. Blue skies, and starry nights. I have see ash from volcanoes where the sun turns red, so I know the scale, and here it is no ash. I have spoken with friends around Europe, and nobody has seen any ash plume. (except Iceland of course)

No, no, this is not the end times you have been reading about. This is the DAWN of a new age of travel! A GLORIOUS adventure on the high seas! See the world ANEW! Why measure your transatlantic travel in hours when it can be measured in DAYs or even WEEKS? Relive a bygone era when it was the JOURNEY that mattered most, not the destination. After a lazy brunch, take a mid-morning stroll on the upper deck in your best pinstripes, while your lady swings her parasol without a care in the world. Dine on the finest cuts of meat, drink the finest wines! Try your luck at the baccarat tables! End your evening with a stout cigar, staring blissfully toward the star filled night sky. It's the future!

Too right, AC! As I flew from Vienna to Nuremberg via Munich just over a week ago, I was thinking the same thing. Much smoother and more comfortable way to travel, and quick enough that shorter trips like that are still within a reasonable time frame.

Sending multiple 50M aircraft into ash clouds to prove what we already knew: that even a brief encounter with volcanic ash will fuck your turbines up but good. And your surfaces. And your Plexiglass. And your ventilation system. And and and...

This is all a ploy by Apple to stop Europeans flying to the USA to buy iPads, after the worldwide launch was delayed!

Its not clear whether Jobs has actually placed iNukes in the Icelandic volcano to cause the eruption or if Apple have teamed up with the CIA, SPECTRE, THRUSH, SkyNet and the Milk Marketing Board to hack computers and exaggerate the threats!! Maybe that's not ash on the computer projections - its the famous Reality Distortion Field!!!

Expect the ban to persist until the end of May!!!!

Now I expect all the Apple fanbois will crawl out of the woodwork and start trying to deny the obvious truth, and I'll be modded down faster than an Airbus with both engines on fire. If Microsoft had done this everybody would be up in arms!!!!!

Nobody seems to be talking about the effect that this volcano will have of the weather. Previous large eruptions have caused mini ice ages.

BoingBoing brought it up [boingboing.net]. They say it's too early to be certain, but so far, the latitude of the eruption seems to be high enough that the ash isn't going to block enough solar radiation to cause any noticeable impact. They point out how eruptions at high latitudes, even huge ones like Mt. St. Helens, have very little impact on climate, whereas smaller ones at low latitudes have a much larger one.

There has long been a theory that the upper atmosphere condensation caused by jets affects the temperature on the ground. If the ash cloud has only a small effect, the lack of contrails may cause a substantial heat increase over the next few weeks.

On the other hand the lack of aircraft contrails after 9/11 was said to result in a marked increase in temperature. It'll be interesting to see if climate modeling accurately predicts the outcome on the next couple of years of weather.

Some Spanish airports are now open again. Madrid is open The ash cloud has moved north. But the volcano is still erupting, ejecting ash to a height of 4Km. The northwestern part of Europe is going to be grounded for a while.

There are still a few transatlantic liners.
If you're stuck in Europe, the Queen Mary 2 sails from Southampton to New York in four days [cunard.com]. There's already a waiting list, but it's quite possible that some people planning to take the trip as a cruise can't get to Southampton, and space may open up.

So they send up half a dozen flights without problems, but this doesn't prove anything. The ash is not evenly distributed; it appears to be in layers in the atmosphere. If you fly up or down through a layer the exposure is brief and you don't see a problem. But if ATC unknowingly tell an aircraft to fly at the same altitude as a layer of ash then you have a big problem.
The bottom line is that a few flights prove nothing. If the risk to a single flight is 1% then you won't see anything, but when you restart aviation aircraft will be dropping out of the sky.

Yes and those were at least back then mostly powered by ICE, which would have had air filters (even if just a bit of cloth) and don't depend on fragile, fine turbine blades cranking at 10K rpm; but instead had relatively robust pistons of steel and iron. Dust will harm and ICE but it causes premature ware one pistons, rings, liners, values, guides, and any thing else being lubes from a common oil sump where dust might get into the oil (also filtered during operation). A Jet is a little or turbo prop is a

I don't know if you know this, but prop planes are still powered by IC engines, that's why they have a giant prop instead of turbine blades. As such, they still take off from dusty areas just fine. The trouble is the quantity of fine ash - there is a shitload of it during an eruption, and this is a very long eruption.

The problem with ash is that it is extremely fine yet very hard. Air filters good enough to block it clog very quickly, after which point your IC engine seizes up. Also, those "relatively r

The real worry is about idiot managers of incompetent airlines who want to gamble on this.

Sounds like Ural Airlines, which tried to fly from Moscow to Rome. They thought that they were being smart by flying below the ash cloud, but they forgot to consider the increased fuel consumption this would cause. While en-route they had to contact the Vienna air traffic controller to ask for an emergency landing, since there was almost no fuel left.

I'm just surprised they actually got their flight plan approved, since Austria (among others) had their entire airspace closed at the time. Or maybe they didn'

It's not that bad is is? I mean, you just have to split the name into logical parts Eyja-fjalla-jökull. There is also a nice example of pronounciation at the wikipedia entry [wikipedia.org], sounding something like Eva-ley-kull.

Thanks to your comment I read the Wikipedia article [wikipedia.org] in its entirety and the below excerpt is phenomenal:

Despite the lack of time, [Captain Eric] Moody made an announcement to the passengers that has been described as "a masterpiece of understatement":

Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them under control. I trust you are not in too much distress.